The present invention relates to a magnetic disk apparatus and more particularly to a magnetic disk apparatus attaining reduction of power consumption while maintaining reliability and performance.
Heretofore, a magnetic disk apparatus or a magnetic hard disk drive has a narrow gap (hereinafter referred to as xe2x80x9cflying heightxe2x80x9d) between a magnetic head slider and a magnetic disk about 20 to 50 nm required from high recording density. The narrowness of the flying height contributes to improvement of the recording density but increases a possibility that the magnetic head slider comes into contact with the magnetic head. Accordingly, there is a possibility that data recorded on the magnetic disk is destroyed due to crash at the worst.
On the other hand, the magnetic disk apparatus has a rotational speed of the magnetic disk increased to about 10,000 rpm due to a demand for high performance. The increased rotational speed of the magnetic disk contributes to improvement of the performance but increases power consumption of the magnetic disk apparatus and further there is a possibility that heat generated by the magnetic disk apparatus is increased.
Further, in recent years, mobile computers having the portability regarded as important are used increasingly and it is desired that the power consumption is reduced when a magnetic disk is mounted in a note-type personal computer or the like.
In order to solve the above problems, the following techniques have been proposed.
(1) A technique that a magnetic disk is rotated at a rotational speed lower than that at the time of recording and reproduction when a magnetic head element or a read/write element does not make recording or reproduction to the magnetic disk (hereinafter referred to as an idle time). This technique reduces the rotational speed of the magnetic disk in the idle time and accordingly the power consumption of the magnetic disk apparatus can be reduced. This technique is described in, for example, JP-A-11-45495.
(2) A technique that the magnetic head slider has the flying characteristic that the flying height thereof is maximized at a rotational speed lower than a normal rotational speed of the magnetic disk and the rotational speed of the magnetic disk is reduced in the idle time. In this technique, since the magnetic head slider has the flying characteristic that the flying height thereof is maximized at the rotational speed lower than the normal rotational speed, the possibility that the magnetic head slider comes into contact with the magnetic disk is reduced even when the rotational speed of the magnetic disk is reduced. Accordingly, the reliability of the magnetic disk apparatus can be ensured. At the same time, in this technique, since the rotational speed of the magnetic disk is reduced in the idle time, the power consumption of the magnetic disk apparatus can be reduced. This technique is described in, for example, JP-A-10-50020.
The technique of reducing the rotational speed of the magnetic disk as described in (1) has a problem that the possibility that the magnetic disk comes into contact with the magnetic disk is increased and accordingly the reliability of the magnetic disk apparatus is influenced greatly although the rotational speed of the magnetic disk can be reduced to thereby reduce the consumption power of the magnetic disk apparatus.
(2) The technique that the magnetic head slider has the flying characteristic that the flying height thereof is maximized at the rotational speed lower than the normal rotational speed of the magnetic disk and the rotational speed of the magnetic disk is reduced in the idle time as described in (2) has a problem that a return time required until the writing/reading operation can be made actually after a processing instruction for writing/reading has been received during the idling period is long although the power consumption of the magnetic disk can be reduced while the reliability thereof can be maintained by the provision of the flying characteristic of the magnetic head slider that the flying height thereof is maximized at the rotational speed lower than the normal rotational speed.
It is an object of the present invention to solve the problems in the prior art by providing a magnetic disk apparatus attaining reduction of power consumption while maintaining reliability and performance.
In order to solve the problems, the present invention comprises the following structure.
According to the present invention, the magnetic disk apparatus including a magnetic head slider in which a magnetic head element is mounted, a magnetic disk to which recording and reproduction of data are made by means of the magnetic head element, and a spindle motor which rotatably supports the magnetic disk, comprises control means for controlling the rotational speed of the magnetic disk in each proper idle time that recording or reproduction is not made after completion of recording or reproduction to the magnetic disk by the magnetic head element until next recording or reproduction time.
Further, according to the present invention, in the magnetic disk apparatus including a magnetic head slider in which a magnetic head element is mounted, a magnetic disk to which recording and reproduction of data are made by means of the magnetic head element, and a spindle motor which rotatably supports the magnetic disk, the magnetic head slider has a flying characteristic that a flying height thereof is increased at a rotational speed of the magnetic disk lower than that at the time of the recording and reproduction, and the magnetic disk apparatus comprises control means for stepwise reducing the rotational speed of the magnetic disk in each proper idle time that recording or reproduction is not made after completion of recording or reproduction to the magnetic disk by the magnetic head element until next recording or reproduction time.
Furthermore, according to the present invention, in the magnetic disk apparatus including a magnetic head slider in which a magnetic head element is mounted, a magnetic disk to which recording and reproduction of data are made by means of the magnetic head element, and a spindle motor which rotatably supports the magnetic disk, the magnetic head slider has a flying characteristic that a flying height thereof is increased at a rotational speed of the magnetic disk lower than that at the time of the recording and reproduction, and the magnetic disk apparatus comprises control means for stepwise reducing the rotational speed of the magnetic disk in each proper idle time that recording or reproduction is not made after completion of recording or reproduction to the magnetic disk by the magnetic head element until next recording or reproduction time and setting a longest idle time at a rotational speed of the magnetic disk in which the flying height of the magnetic head slider is maximized.